Method for coating a surface of a track component, in addition to a track component

ABSTRACT

A method for coating a surface of a track component with a coating containing aluminum by means of an arc spraying process. In order to form a coating that exhibits a high resistance to sliding and abrasive wear, aluminum and silicon are applied to the surface in a ratio of 3:2≦Al:Si≦4:1 by an arc spraying process.

The invention relates to a method of coating a surface of a trackcomponent having an aluminum-containing coating by means of an arcspraying process. The invention also relates to a track component, suchas a switch component, with an aluminum-containing coating applied by anarc spraying process.

A slide chair is known from DE 38 05 963 A2 in which a lubricant isapplied by a plasma or flame spraying process, the lubricant containingmolybdenum or ternary or quarternary alloys based on Co or Ni,optionally with additives such as Mo, Cr and/or Si.

A sectional rail for a monorail having a bearing surface which ishorizontal in cross section and to which a metal is applied by a flamespraying or arc spraying process can be found in DE 38 41 044 C2. Themetal surfacing in that case comprises an adherence layer and a wearlayer which contains 10% to 25% chromium. The adherence coating itselfis preferably composed of 60% to 90% nickel and 10% to 40% aluminum. Thethickness of the metal coating can be between 0.3 mm and 5 mm.

The disadvantage of a corresponding metal coating applied by an arcspraying process is that it is double-layered, the sliding and abrasivewear not being substantially increased in comparison to those coatingsconsisting of molybdenum which are applied by flame spraying, yet aresingle-layered.

The present invention is based on the problem of further developing amethod of coating a surface of a track component as well as the trackcomponent itself in such a way that a coating can be formed in atechnically simple manner, the coating having a high resistance tosliding and abrasive wear and, in particular, a high corrosionresistance to atmospheric electrolytes such as e.g. salt water orde-icing agents. A good adherence should also be provided.

According to the invention, the problem is substantially solved, by amethod of the aforementioned type, in that aluminum and silicon areapplied to the surface in a ratio of 3:2≦Al:Si≦4:1 by arc spraying. Inparticular, aluminum is applied in a ratio of 3:1 to silicon.

The thickness of the coating comprising or containing aluminum andsilicon should be between 0.2 mm and 2 mm, in particular in the rangebetween 0.8 mm and 1.5 mm. A good adherence was shown when the coatingwas applied to a high-strength steel such as St 52.

According to the invention, aluminum and silicon are applied, inparticular, to switch parts such as slide chairs or switch locks, suchas can be found e.g. in EP 0739804, whereby the desired higherresistances to sliding and abrasive wear as well as high corrosionresistance can be obtained even with extremely small thicknesses.Substantial advantges are thereby provided, in particular in comparisonto the previously known coating substances such as molybdenum andbronze. However, advantages are also shown in comparison to themulticoating structure according to DE 38 41 044 C2, insofar as only onecoating is required which also meets all requirements when the coatingthicknesses are only between 0.8 mm and 1.5 mm.

Cost-related advantages also result in comparison to e.g. nickel andaluminum or molybdenum substances, which are used according to the stateof the art.

A track component such as a switch component or switch locking partshaving a coating containing aluminum applied by an arc spraying processis distinguished in that this coating comprises or contains aluminum andsilicon in a ratio of 3:2≦Al:Si≦4:1, in particular, wherein aluminum isin a ratio of 3:1 to silicon.

In this case, a sheathed wire having a sheathing of aluminum andpowdered silicon incorporated therein is preferably used as spray wirefor the arc spraying process. Furthermore, the melted aluminum andsilicon should be applied to the surface at a feed pressure of 2 to 4bar over atmospheric pressure to obtain the desired adhesion. Thecoating should thereby be applied to the surface with a thickness d of0.2 mm≦d≦2 mm, preferably 0.8 mm≦d≦1.5 mm.

The sheathed wire serving as the spray wire is conveyed to the arc witha wire feed rate V, where 1 m/sec.≦V≦15 m/sec., preferably 6 m/sec.≦V≦8m/sec., whereby a voltage difference U, where 30 V≦U≦50 V, in particularU≈40 V, should be set between the spray wires. To melt the aluminum andsilicon, a current I, where 200/A≦I≦600 A, in particular 250 A≦I≦500 A,should flow between the spray wires.

Further details, advantages and features of the invention can not onlybe found in the claims, the features found in said claims, alone or incombination, but also in the following description of a preferredembodiment found in the drawing.

A basic representation of a device for applying a spray coating to atrack part in the form of a slide chair 10 is shown in the only figure.A device 12 in which spray wires 18, 20 can be moved together relativeto the slide chair 10 via wire feed devices 14, 16 is directed towardsthe slide chair 10. Since a voltage V of between 30 V and 50 V, inparticular about 40 V, prevails between the spray wires 18, 20, an arc22 can form between the spray wires 18 and 20 to melt the arc material.This takes place, as a result of the prevailing voltage difference whenan arc forms between the spray wires 18, 20, which, due to theirdifferent potentials, have the function of an anode and cathode in thearea of the tips 22. A current I between 200 A and 600 A thereforeflows, with the result that a temperature of about 4000° C. is produced,which leads to the desired melting of the spray wires. Gas issimultaneously conveyed to the arc 22 between the spray wires 18, 20 viaa channel 24 at a pressure of preferably 3 to 4 bar, so that a spray jet26 is formed which is deposited as a coating 28 on the slide chair 10.

To ensure that the coating 28 is formed uniformly and to the desiredextent, the device 12, in direction of arrow 30, and/or the slide chair10, in direction of arrow 32, are moved relative to one another at adesired velocity V_(G), where 600 mm/sec.≦V_(G)≦1300 mm/sec.

The spray wires 18, 20 are sheathed wires having a sheathing consistingof aluminum with powdered silicon therein. The ratio of aluminum andsilicon is thereby set in such a way that the spray jet 26 has acomposition of aluminum and silicon in the ratio of between 3:2 and 4:1,in particular 3:1.

As a result, the coating 28 obtains a high resistance to sliding andabrasive wear as well as a high corrosion resistance to atmosphericelectrolytes such as salt water and de-icing agents. Furthermore, a highadherence results on the surface of the slide chair.

The sheathed wires or spray wires 18, 20 are fed to the arc 22 via thefeed device 14, 16 at a velocity of, in particular, 30 mm/sec.≦V≦100mm/sec.

1. A method of coating a surface of a track component with a coating containing an aluminum by means of an arc spraying process, characterized in that aluminum and silicon are applied to the surface in a ratio of 3:2≦Al:Si≦4:1 by an arc spraying process.
 2. The method according to claim 1, characterized in that the aluminum and silicon are applied in a ratio of Al:Si≈3:1.
 3. The method according to claim 1, characterized in that a sheathed wire having a sheathing of aluminum and powdered silicon incorporated by it is used as spray % Wire for the arc spraying process.
 4. The method according to claim 1, characterized in that the melted aluminum and silicon are applied to the surface at a feed pressure of 2 to 4 bar over atmospheric pressure.
 5. The method according to claim 1, characterized in that the coating is applied to the surface with a thickness d of 0.2 mm≦mm≦d≦2 mm, preferably 0.8 mm≦d≦1.5 mm.
 6. The method according to claim 3, characterized in that the sheathed wires as spray wires are fed to the arc at a wire feed velocity of 1 m/sec.≦V≦15 m/sec., preferably 6 m/sec.≦V≦8 m/sec.
 7. The method according to claim 3, characterized in that a voltage difference U, where 30 V≦U≦50 V, in particular U≈40 V, is set between the spray wires.
 8. The method according to claim 3, characterized in that a current I, where 200 A≦I≦600 A, in particular 250 A≦I≦500 A, flows between the spray wries in order to melt them.
 9. A track component (10) such as a switch component having an aluminum-containing coating (28) applied by an arc spraying process, characterized in that the coating (28) comprises or contains aluminum and silicon in a ratio 3:2≦Al:Si≦4:1.
 10. The track component according to claim
 9. characterized in that the track component (10) is a slide chair or switch lock.
 11. The track component according to claim 9, characterized in that the coating of aluminum and silicon is applied to the track component (10) in the ratio 3:1.
 12. The track component according to claim 9, characterized in that the coating (28) has a thickness d, where 0.2 mm≦d≦2 mm, preferably 0.8 mm≦d≦1.5 mm.
 13. The track component according to claim 9, characterized in that the coating (28) is applied to a high-strength steel St
 52. 14. The track component according to claim 9, characterized in that the coating (28) is a single coating. 